Take a look at baseball card holders, which come in various configurations for three ring binders. They're a bit bigger than a business card, but they should work well.
As for putting your Turbobs in plastic prisons - please don't. Big plastic cases make you look like a pretentious tool, so you may as well go whole hog and send 'em to VGA for grading. If you want to protect the box from fingerprints, plain ol' shrinkwrap does the job just fine; if you want protection from more aggressive damage, get less careless friends.